[PATCH v2] drm/bridge: adv7511: fix crash on irq during probe

[Alvin Šipraga]

From: Mads Bligaard Nielsen <bli at bang-olufsen.dk>

Moved IRQ registration down to end of adv7511_probe().

If an IRQ already is pending during adv7511_probe
(before adv7511_cec_init) then cec_received_msg_ts
could crash using uninitialized data:

    Unable to handle kernel read from unreadable memory at virtual address 00000000000003d5
    Internal error: Oops: 96000004 [#1] PREEMPT_RT SMP
    Call trace:
     cec_received_msg_ts+0x48/0x990 [cec]
     adv7511_cec_irq_process+0x1cc/0x308 [adv7511]
     adv7511_irq_process+0xd8/0x120 [adv7511]
     adv7511_irq_handler+0x1c/0x30 [adv7511]
     irq_thread_fn+0x30/0xa0
     irq_thread+0x14c/0x238
     kthread+0x190/0x1a8

Fixes: 3b1b975003e4 ("drm: adv7511/33: add HDMI CEC support")
Signed-off-by: Mads Bligaard Nielsen <bli at bang-olufsen.dk>
Signed-off-by: Alvin Šipraga <alsi at bang-olufsen.dk>
---
Changes in v2:
- rebase on latest drm-misc-fixes
- no other changes
- RESEND
- Link to v1: https://lore.kernel.org/r/20231014-adv7511-cec-irq-crash-fix-v1-1-3389486c8373@bang-olufsen.dk
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 8be235144f6d..6fc292393c67 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1277,17 +1277,6 @@ static int adv7511_probe(struct i2c_client *i2c)
 
 	INIT_WORK(&adv7511->hpd_work, adv7511_hpd_work);
 
-	if (i2c->irq) {
-		init_waitqueue_head(&adv7511->wq);
-
-		ret = devm_request_threaded_irq(dev, i2c->irq, NULL,
-						adv7511_irq_handler,
-						IRQF_ONESHOT, dev_name(dev),
-						adv7511);
-		if (ret)
-			goto err_unregister_cec;
-	}
-
 	adv7511_power_off(adv7511);
 
 	i2c_set_clientdata(i2c, adv7511);
@@ -1311,6 +1300,17 @@ static int adv7511_probe(struct i2c_client *i2c)
 
 	adv7511_audio_init(dev, adv7511);
 
+	if (i2c->irq) {
+		init_waitqueue_head(&adv7511->wq);
+
+		ret = devm_request_threaded_irq(dev, i2c->irq, NULL,
+						adv7511_irq_handler,
+						IRQF_ONESHOT, dev_name(dev),
+						adv7511);
+		if (ret)
+			goto err_unregister_audio;
+	}
+
 	if (adv7511->info->has_dsi) {
 		ret = adv7533_attach_dsi(adv7511);
 		if (ret)

---
base-commit: 335126937753844d36036984e96a8f343538a778
change-id: 20231014-adv7511-cec-irq-crash-fix-6fdd9093dc7a